Known housings for semiconductor components include lead pieces embedded into a plastic housing composition. External contact areas of the lead pieces are kept free of the plastic housing composition and are arranged on an underside of the housing. Housings of this type are also called “leadless packages.” Surface-mount housings of this type have hitherto been positioned onto a printed circuit board of a superordinate circuit. For this purpose, corresponding contact pads which correspond in size, arrangement and form to the lead pieces or external contact areas of the lead pieces and are kept free of plastic housing composition are provided on the printed circuit boards. The surface-mount housings are oriented in such a way that a soft solder connection, for example, composed of SnPb or SnAgCu, can be realized between the two areas in a soldering operation.
The increasing miniaturization of the components compels a continuous reduction of the quantity of solder available for these connections. Since the housings of the semiconductor components and the printed circuit boards comprise different materials, shear stresses arise during thermal loadings and affect the connections between semiconductor component or the external areas and the soft solder connections of the semiconductor components with the contact pads of the printed circuit boards. The shear stresses can contribute to the complete failure of the overall circuit if one of these solder connections is interrupted on account of the thermal loadings.
The thermal loadings are caused by the different coefficients of thermal expansion (CTE), which are approximately 3 ppm/° C. for semiconductor chips composed of silicon, 10 ppm/° C. for the plastic housing composition, approximately 18 ppm/° C. for copper and approximately 18 ppm/° C. for the printed circuit board material. Any difference in thermal expansion between the printed circuit board and the component to be mounted leads to such shear stresses in the soldered joint lying between component and printed circuit board.
If the number of thermal cycles increases, then this leads to fatigue of the soldered joint and failure of the component or an interruption of the electrical connection between semiconductor component and printed circuit board can thus occur. This risk is also increased if the solder volumes are reduced and the sizes of the housings simultaneously increase in terms of their absolute dimensions. This effect occurs particularly in the case of the above mentioned surface-mount housings with lead pieces, such that their field of use is limited on account of the unreliable surface mounting possibilities.
A nonconductive film with nanopores is known which mechanically connected and hold together first and second electronic parts. The film has metal-filled nanopores extending through the thickness of the film, such that the two parts are contact-connected by the metal at least in some of the pores, wherein the film comprises a polymer film. The disadvantage of this construction is that the metal-filled nanopores cannot be assigned to one of the two parts in a targeted manner and are not fixed on one of the two parts, rather the contact-connection is left more or less to chance, such that precisely between the two parts one or else a plurality of metal-filled nanopores are positioned which produce an electrical pressure contact only when a corresponding contact pressure is exerted on the first and second electronic parts. Consequently, the metal-filled nanopores of a polymer film do not provide a reliable electrical connection between the parts that are to be electrically connected, the dependence on chance as to what region of the film with what number of nanopores falls precisely into the contact-connection region between two parts not ensuring a reliable connection even if thermal shear stress does not play a part in this connection technique based on pressure contact-making.